1. Field of the Invention
This invention relates to an image processing method and apparatus, and more particularly to an image processing method and apparatus for processing a decorated character image formed by arranging decorated characters formed by decorating arbitrary characters as desired, on an arbitrary background.
2. Prior Art
In general, in an image processing method and apparatus of this kind, for instance, when a color image is processed, the color of each pixel of the color image is represented by gradation values of respective basic colors for use in composing various colors. For the color of each pixel of a display image, for instance, three colors R (red), G (green), and B (blue) are defined as the basic colors, while for the color of each pixel of a print image, three primary colors C (cyan), M (magenta), and Y (yellow), or the three primary colors plus a color K (black) are defined as the basic colors. A color image is represented by image data in which the color of each pixel of the color image is expressed by decomposing it into gradation values indicative of respective gradation (gray) levels of the basic colors. As a result, the colors of the pixels of the color image are expressed by a so-called additive or subtractive color mixing process. Further, for instance, when a unicolored monochrome (e.g. black and white) image is processed, the colors (gray tones) of pixels of the monochrome image are represented by gradation values of the pixels.
Therefore, in an image processing method and apparatus of the above-mentioned kind, if a color image is to be processed, arbitrary colors are set, or if a monochrome image is to be processed, arbitrary gradation values (gray tones) are set, to portions of the image to be processed (elements forming the image to be processed: image elements or the like) such that the image can be formed or output (displayed, or printed) according to the settings. It should be noted that in the following description, a color image and a monochrome image are not particularly distinguished from each other since the monochrome image can be regarded as color image of a type which is small in the total number of gradation values that can represent the color of the image (i.e. low in resolution). For this reason, let it be assumed that in the following description, the concept of “color” includes one represented only by gray tones (gradation values), that is, different colors include identical colors different from each other only in gray tone (gradation value), for instance. Further, when an image contains a lot of colors (including gray tones, as described above) to be represented, the image is described as “an image having a high resolutions”, whereas when an image contains a small number of colors to be represented, the image is described as “an image having a low resolutions”.
Now, when there are many kinds of colors which can be set, and further when there are a lot of image elements whose color can be set separately, it is a very troublesome and time-consuming work to select desired colors one by one from the many kinds of colors and set them for the image elements. To eliminate this inconvenience, the present assignee proposed a setting method which is capable of selectively setting a predetermined default color adapted to an image or impression of a keyword or the like instead of setting colors for all the elements of a character image, thereby saving part of the trouble of effecting settings of the above-mentioned kind (Japanese Patent Application No. 10-54432). The same setting method can be employed also when a decorated character image is formed by arranging decorated characters formed by decorating arbitrary characters as desired, on an arbitrary background (see FIGS. 5 and 6). According to this setting method, it is possible to effect ordinary settings required for forming a decorated character image, simply by selecting a predetermined mode (color mode) as one adapted to a whole image or impression of the decorated character image, or thereafter further arbitrarily changing only colors of desired elements, thereby saving part or whole of a troublesome setting operation. (It should be noted that throughout the especification and claims appended thereto, the term “character image” is used to mean “image of at least one character”.)
However, depending on a combination of predetermined default colors set for individual image elements, or a combination of a default color and a color set as desired, it is sometimes difficult to discern elements (image elements) from each other. For instance, generally, a character portion corresponding to a character or characters of a decorated character image is desired to be made conspicuous against a background thereof, so that a default color set to the character portion is also made conspicuous against a default color set for the background. Further, similarly, a decorative portion corresponding to a portion for decorating the character portion of the decorated character image is also desired to be made conspicuous against the background thereof, so that a default color for the decorative portion is also set conspicuous against the default color for the background (see FIGS. 5 to 7). Therefore, a default color for the character portion and a default color for the decorative portion are liable to become identical or similar (similar colors include different colors but having gradation values identical or close to each other: identical or similar colors in the case of a monochrome image) to each other, and when settings of colors of both of the character portion and the decorative portion are omitted, a combination of default colors are set for the character portion and the decorative portion, respectively, which often makes it difficult to distinguish the color of the character portion from the color of the decorative portion. Further, also when one of a character color and a decorative color is set as desired, the user usually selects a color conspicuous against a background color, so that the combination of a default color and a color set as desired is liable to be a combination of colors identical to or similar to each other. This is likely to result in a combination of colors which makes it difficult to discern a character portion from a decorative portion.
Further, it is often desired to verify a decorated character image formed by the present apparatus for being output by an output device of another apparatus, by using an output device of the present machine. If the output device of the present apparatus is capable of outputting an image which is higher in resolution than the decorated character image formed, i.e. if the output resolution of the output device of the present apparatus is higher than the resolution of the decorated character image, the decorated character image can be output as it is, without causing any problem. On the other hand, if the output resolution of the output device of the present apparatus is lower than the resolution of the decorated character image, only a smaller number of colors dependent on the output resolution of the output device of the present apparatus can be output, and hence it is required to convert the decorated character image to an image formed of the smaller number of colors (this processing will be referred to hereinafter as “color-limiting processing) and then output the resulting image (hereinafter referred to as “limited-color outputs”). For instance, when a decorated character image of colors of a larger number of gradation levels (high in resolution) is to be output to an output device which is capable of outputting an image of colors of a smaller number of gradation levels (including monochrome as mentioned above) (i.e. which has lower output resolution), it is required to carry out the color-limiting processing to convert the decorated character image higher in resolution to an output image lower in resolution, and the limited-color output to output the output image subjected to the color-limiting process.
The same things occur within an identical image processing apparatus. For instance, a decorated character image prepared (as a print image) for being printed by a printing device (printing means) higher in output resolution may be desired to be verified or checked before printing by causing the image to be displayed by using a display device (display means) lower in output resolution. This corresponds e.g. to a case in which a color print image is desired to be verified or checked on a monochrome display screen. Further, preliminarily for subsequent processing, a decorated character image formed at a higher resolution may be desired to be output at a lower resolution, intentionally, as in the case of a monochrome printing being carried out to check on the layout or impression of a color print image to be formed after printing, to thereby save the cost of a preview print.
However, in these cases. i.e. when a decorated character image provided (e.g. formed) for being output to an output device having a higher output resolution is output to an output device (output means, such as display means) having a lower output resolution, or when such a decorated character image is intentionally output at a lower output resolution, the image output (by coloring-limiting output) after subjecting the prepared decorated character image to the color-limiting processing can be difficult to discern, i.e. may not provide information sufficient for a user to grasp what kind of image it is. This is mainly due to difficulty of discrimination between elements of composition of the image (image elements). For instance, a character portion corresponding to characters of the decorated character image and a decorative portion corresponding to a portion subjected to character decoration are both desired to be made conspicuous against the background, so that colors set for these portions are liable to become identical or similar (in the sense defined as above) to each other. In such a case, if a decorated character image having a higher resolution is output for limited-color output in a manner simply adapted to the lower resolution of a lower resolution output device without further processing, a plurality of image elements (e.g. one or more character portions and one or more decorative portions) of the decorated character image which are originally distinguished by the higher resolution are caused to have an Identical color or a similar color to each other. Thus, one or more boundaries dividing the plurality of image elements can become unable to be discerned, which makes it impossible to identify the output image.